Add xterm itegration

* Move to TypeScript from legacy JavaScript
* Add support of xterm.js
* Hterm is still available for backward compatibility

js/typings/hterm/index.d.ts

@@ -0,0 +1,47 @@
+export interface Terminal {
+    io: IO;
+    onTerminalReady: () => void;
+
+    getPrefs(): Prefs;
+    decorate(HTMLElement);
+    installKeyboard(): void;
+    uninstallKeyboard(): void;
+    setWindowTitle(title: string): void;
+    reset(): void;
+    softReset(): void;
+}
+
+export interface TerminalConstructor {
+    new (): Terminal;
+    (): Terminal;
+}
+
+
+export interface IO {
+    writeUTF8: ((data: string) => void);
+    writeUTF16: ((data: string) => void);
+    onVTKeystroke: ((data: string) => void) | null;
+    sendString: ((data: string) => void) | null;
+    onTerminalResize: ((columns: number, rows: number) => void) | null;
+
+    push(): IO;
+    writeUTF(data: string);
+    showOverlay(message: string, timeout: number | null);
+}
+
+export interface Prefs {
+    set(key: string, value: string): void;
+}
+
+export interface Storage {
+}
+
+export var Terminal: TerminalConstructor;
+
+// @TODO: is there better way?
+// exported variables are forced to be read-protected.
+declare global {
+    var hterm: {
+        defaultStorage: Storage;
+    };
+}

js/typings/htermLib/index.d.ts

@@ -0,0 +1,11 @@
+export interface Storage {
+}
+
+export interface Memory {
+    new (): Storage;
+    Memory(): Storage
+}
+
+export var Storage: {
+    Memory: Memory
+};